X louis reynolds



' Jan. 10, 1928.

J. L. REYNOLDS SIGNAL CONTROLLING APPARATUS Filed April 1, 1927 2 Sheets-Sheet l Him f1 In entor M3 "41' Attorney Jan. 10, 1928. v 1,655,843

J. L. REYNOLDS S IGNAL CONTROLLING APPARATUS Filed April 1, 1927 2 Sheets-Sheet 2 Patented Jan. 1d, 192%.

Umrsn stares PATENT OFFICE.

JOHN LOUIS REYNOLDS, OF LONG ISLAND CITY,'I TEW YORK, ASSIGNGB, BY MESNE AS- SIGNMENTS, TO ELECTRICAL RESEAECH PRODUCTS INQ, A CORPORATION OF DELA- WARE.

Application filed April 1,

This invention relates to signal control apparatus and with particularly to alarms controlling apparatus for use in connection with sound recording mechanism.

The invention exhibits its practical utility when employed in sound recording systems wherein the sound record is made in a mechanical medium such as wax or other element having an impressionable surface, the sounds being perman ently represented in the form of a continuous wavelilre cutting of varying amplitude. hen records of this type are being produced, it frequently happens that the recording stylus, the point of which moves in a horizontal plane, is subjected to an excessive amplitude of movement, for example, that occurring in the recording of unusually loud sounds, resulting a socalled overcutting. In some cases this overcutting may result in the breaking of the wall between adjacent grooves rendering the record worthless as a master record. This difficulty is of much pecuniary moment where the works of great artists are being recorded, and. where a defect in the forming of the master record may occasion the outlay of large expenditures of money for repetition of the recording process. Un-

somc continuous check is provided on the functioning of the recording stylus such. defects as overcutting, are not revealed until the complete performance of the artist has been recorded... It has been the practice heretofore to follow visually, by means of microscopes or the like, the action of the cul'tii'ig stylus. It has been found. however, that this visual. check is not in all cases reliable, and necessitates the employment of skilled operators who must continually watch and instantaneously detect overcutting when it occurs. i

The invention has therefore for its principal object the provision of means for corn tinuously following the action of a record 4:: ing stylus and for automatically giving signails, eitaer visuahaudible or both. when the stylus exceeds a maximum predeterntiined ampl' do of movement.

,tur of the inventioii resides in an .1 which effective SIGNAL-CONTROLLING APEARATUS.

192?. Serial No. 180,325.

control an alarm at the instant a recording stylus begins to over-cut.

Another feature of the invention is concerned with a relay arrangement for insuring the closure or opening of a control circuit in response to very short signal impulses.

A still further feature relates to the combination of a vacuum tube oscillator which is normally just below the point of oscillation but which responds to a single transient impulse and generates sustained current oscillations which may be utilized to permanently control a visual or audible signal.

Other features and advantages of the invention, not specifically set forth at this point, will be revealed by a consideration of the description of one mode of practicing the invention as given hereinafter and as pointed out with particularity in the appended claims. I

Referring to the drawing, Fig. 1 shows an. electromagnetic sound recording device with which is associated an electro-optical system for controlling the alarm circuit.

Fig. 2 illustrates schematically the electro-optical system disclosed in Fig. 1.

Fig. 3 shows a novel form of a vacuum tube relay for controlling an electric circuit. i i

Fig. 4 shows a magnified section of a disc type sound record illustrating one form of sound cutting.

Similar pieces of apparatus disclosed in the several figures of the drawing bear the same reference characters.

For the purposes of ilhistrating one mode of using the invention, it has been chosen to .describethe same in connection with a sound recording system wherein electromechanical devices are employed for the purpose of translating the sound variations into correspending 5 cuttings in a wax record. For this purpose when the microphone 1, has been properly positioned for the reception of the sound waves to be recorded, the motor 2, is started and brought up to speed with tl stylus in contact with the recording surace 4i llhefsound waves impingingu w the microphone 1 cause esrrespending variations in the grid potential of the amplitier A which is preferably of the electron discharge type and which produces in its output circuit voltages which are undistorted in so far as they correspond to the variations in intensity and quality of the sound waves.

Associated with the output circuit of the amplifier A is the electromagnetic translator It which may be of any well-known construction adapted to move the recording stylus point laterally across the record a. A special form of translator shown in Fig. 1, butit is understood .that the drawing is essentially schematic in this respect. The iecordertranslator showin. comprises a magnet ti to which are attached, in any suitable manner the laminated pole-pieces T and 8. The tips ot the pole-pieces are preferably so shaped as to conform to the shape ot the ends of armature shown. the armature beii'ip; siipported in any suitable manner for vibration between the pole-pieces. Surrounding the armature, but not interfering with the movement thereof, is a winding 9. which is connected in the output circuit oi the amplifier A. Armatureo will there tore be moved toward and away from the poleupieces in accordance with the characteristics of the sound waves striking the microphoi'ie 1. and in the well-known manner, the point 0t stylus 3, which is attached in any suitable manher to the armature, will cut a continuous wave-like groove oi constant depth in the wax record blank 4, the amplitude of the wave at any particular point corresponding to the amplitude of vibration of the stylus point.

When a master record is prepared in accordance with the apparatus shown in Fig. 1 itis desirable for various reasons to ii): a definite limit to the amolitude of movement of the stylus. In a manner this amplitude may be controlled by the amplifier A whose gain may be adjus ed to give the required amplitude ol inovement of the stylus when the loudest sound is impressedupon the microphone. Nevertheless at times, because of varying degrees of hardness oi the blank t El E:

at diilerentpoints a given current from am pl'ifier A. will cause stylus 3 to trace a wave 0t greater amplitude than is required. Attimes this may result in the stylus cutting across from one groove to the preceding adjacent groove as indicated in lt ig. at by the dotted portion 51 between grooves -19 and 50. For the purpose of instantaneously detecting this ove'rcutting an optical system is provided, comprising the small, concave mirror 10 1 and which is fastened in any suitable manner at a convenient point on the stylus 8. his mirror is preferably of aluminum or other light material in order that it may not affect the constants of the reproducer.

Suitably mounted beneath the reproducer arm 11 and movable therewith is a darkbox 12 at one end of which is conveniently mounted the photoelectric cell 13. Between the cell 13 and the mirror 10 is a small lamp 15 giving substantially a point-source of light. The light rays from the source 15 pass thru a smml opening 17 in the righthand end of the dark-box and strike the small mirror 10 upon which they are tocussed by the lens 16. hen the stylus 3 is at restthe rays from the source 15 strike the mirror 10 at its center, as shown in Fig. 2 and are reflected back upon themselves in a straight line. hen the stylus is moved away from its rest position the rays l rom the source 15 are eccentric villi respect to the mirror ill and are reflected to one side or the other as shown.

On either side of the central opening-1i are two other openings 18 and it) which correspond to the maximum allowable amplitude of movement ol the stylus in either dire 'tion. hen the stylus is in any intermediate position, the rays retiected from the mirror 10 do not enter the darlcbog and conseiuiently do not atlcct the cell 12'}. Should the stylus be moved just beyond the allow able maximum, for example, as a result ot over-cuttmg, the rays reflected from mirror 10 will pass thrii one of the openings 18, 19. The rays from mirror 10 utter passing thru opening 19 for example, strike the mirror 20 which is conveniently mounted on the innerlateral wall of the dark-hox in the proper position to retlect the rays toward the plmtoeleciric cell 1 upon which they are tocussed by the lens 22. in asimilar mariner on the o osite lateral interior will ot the diirk boxf is a mirror 21 for refleeting on to the cell 13 the light rays entering the opeiiiing 18. A light batile 1t is pro vided in order that the cell 12? may not be affected by the direct rays ti- 5m the lamp 15;

Referring to Fig. 2 it will be seen that when the mirror 10 is in its central "position (indicated in full lines), the rays reflected from the n'iirror ltl are reiiccted back through the opening 17. When the mirror 10 is'moved to its maximum allowable position in one direction, the rays are reflected through the opening 19 and strike the mirror 21 from which they are reflected and are then foeussed by lens 22 upon the cell 13. Similarly when the mir'or is moved to its maximum allowable position in the opposite direction the rays are reflected thru the opening 18, strike mirror 20, and are reflected to the 'cell 13. It is clear then that. when the stylus 3 begins to move beyond its maximum allowable distance in either direction, the cell 13 receives a sudden impulse of light and its resistance is changed'to correspond. This change in resistance may be utilized to cause the actuation of a bell, the lighting of a lamp, or any other suitable signal to attract the attention of an attendant to the condition in order that the recording process that the space current is insufficient to operate the relay 29. When, however, cell 13 receives a momentary impulse oi light, the

' resistance of the cell is reduced and current .fioWs from the positive pole of battery 26,

lefthand Winding of relay27, conductor 28, anode of the cell 13, conductor 29, resistance 51, to the negative pole of battery 26. The flow of current as traced is in such adirection as to decrease the negative potential of gricl '2l. The left winding oi relay 29 is preferably of a comparatively high resistance and a great numb'erof turns in order that relay 27,1nay attract its armatures in response to a momentary current impulse. As soon as relay 29 operates in the'manner described, a locking is established from positive pole of battery 30, resistance 31, righthand low resistance winding of relay 29,. contacts of key 32, inner contacts of relay 29, to the negative pole of battery 30. This last traced circuit also extends in parallel through the outcr contacts of relay 29 and thence through the signal device Signal 33 therefore remains operated until the iocle.

ing circuit of relay 27 is broken by the.

attendant nianipulatingv key I In the event that the impulse of light is of insufiicient duration to etlect he operation of relay 2?, a. novel form of trigger circuit such as shown in Fig. 3 may be employed. This trigger f circuit comprises a three-electrode regenerative vacuum tube amplifier which is normally maintained just below the point of oscillation. The oscillating circuit of the amplifier shown in Fig. 3, comprises the inductances 35, 36 and the variable condenser 37. The photoelectric cell 13 is connected in a leak circuit across the grid and plate of the amplifier, and has its anode supplied with potential from the same source as supplies the plate potential for the amplifier, namely, battery 39. The potential of the grid 40 is a function of the potential drop in resistance 41, and a function of the potential of battery 42. "With the cell 13v completely dark, the inductances 35 and 36, condenser 37 and battery 42 are so adjusted that the amplifier is just on the verge of generating oscillations, and in response to a slight change 1n good poten tials will sustain these oscillations or spillover as is wellknown in the art. T The resistance l1 and the condenser 43 are of such proportions with regard to the average working resistance of the cell 13 that any potentials impressed upon the grid due to the excitation of cell 13 will leak off comparatively slowly. The resistance 41 and condenser 43 may also be proportioned to facilitate the generation of oscillations.

g When the cell 13 is excited by a momentary impulse of light, for example that due to an excessive movement o't mirror 10 as hereinabove described, the current lowing through the cell from the battery 39 and through resistance 41-1 will be in such a direction as to make grid 4.0 less negative with respect to the filament, causing the amplifier to spill-over and the resulting oscillations will be sustainedin a well-known manner even though the cell 13 becomes dark. The increased current resulting from the sustained oscillations flows through the lefthand winding of relay 44 which is similar to relay 27 of Fig. 1. Relay 44 is also provided with a right-hand low resistance holding winding whichis controlled by key 45. hen key 45 is operated by the attendant the upper contacts thereof open the circuit through the leftwinding of relay i i, thus curtailing the generation of oscillations,

while the lower contacts openthe locking circuit of relay 4a which may thereupon release and disconnect the signal 46 from battery t7. If desired, the condenser shunting the operating winding of relay 44: may be used vi or tuning to the oscillation frequency or for by-passing'the oscillatory currents.

It is understood that the scope of the in-' volition is not to be conhned to the precise elementsshown in the drawing, as various modifications may be madev therein without departing from the spirit and purpose of the inventive idea.

i l hat is claimed is:

1. In combination, an element having an innoressionable surface, a movable device adapted by its movement to translate sound lit) be made in said surface, an electro-optical system, controlled by said element, anda signal to be actuated under control of said electro-optical system.

4. Means for detecting overcutting in a master sound record comprising a light sensitive device actuated by the recording stylus and an alarm automatically actuated by said light sensitive device. 7

5. In combination, a recording stylus, a light beam controlled by the movement of said stylus, a light sensitive cell excited only when said stylus has a predetermined amplitude of movement, and a si 'nal operated under control of said cell.

6. In combination, a movable recording arm, an electromagnetic translatii'ig device, a member to be oscillated by said device, an electrc-optical system comprising a light sensitive cell, and means for exciting said cell only in response to a predetermined movement of said member.

7. In combination, an electromagnetic reproducer, a stylus to be operated by said reproducer, a darlnbox containing a light sensitive element and an optical system, means for actuating said reproducer by sound modulated currents to vibrate said stylus, means carried by said stylus for controlling the excitation of said light sensitive element only when said stylus reaches a predetermined amplitude ofinovement, and a movable recording arm upon which said rcproducer and said darlcbox are mounted.

8. In combination, a vibrating recording stylus, an electro-optical system comprising a. photo-electric cell, a signalling device, a relay for controlling said device, an electron discharge amplifier between said cell and said relay, means associated with said stylus and effective only upon a predetermined amplitude of movement of said stylus to control the excitation of said cell, said relay being responsive to such excitation to cause said signal to be operated. I i

9. illeans for signalling when a recording stylus is overcutting which comprises a mirror fastened to said stylus, a photoelectric cell excited when said mirror assumes a. predetermined position, an electron (lischarge amplifier associated with said cell, a relay connected in the output circuit of said amplifier, said relay being inert when said cell is not excited and adapted to be operated in response to a single momentary cxcitation of said cell, and means for maintaining said relay operated after discontinuance of excitation of said cell.

10. In combination, a recording stylus, a light beam controlled by the movement of said stylus, a photoelectric cell excited when said stylus has a predetermined amplitude of movement, anda signal operated under control of said cell.

11. In combination, a source of light, a light sensitive cell, a device, for generating current oscillations, means for maintaining said device just below the threshold of oscillation when said cell is not excited, means for exciting said cell by a momentary flash of light "from said source to cause said device to startgenerating current oscillations, and means for causing said device to continue generating current oscillations independently ot the excitation of said cell.

12. In combination, an oscillatory circuit comprising a light sensitive cell and a regenerative vacuum tube amplifier, and means for maintaining said circuit just below the threshold of oscillation when said cell is not excited and for causing said circuit to pass the threshold of oscillation and to continue oscillating when said cell is momentarily excited.

13. In combination, a regenerative vacuum tube amplifier adapted to produce current oscillations, a light sensitive device connected to the grid of said amplifier, a combination of elements for maintaining said amplifier on the verge of oscillation when said device is not excited, means for exciting said device by a momentary flash of light to cause said amplifier to produce current oscillations, said combination of elements serving to maintain said amplifier producing current oscillations independently of the excitation of said device.

'14. In combination a recording stylus, a beam of light controlled by themovement of said stylus, a light sensitive cell, means for exposing said cell momentarily to said beam of light when said stylus exceeds a predetermined amplitude of movement, a rc generative electrondischarge amplifier, adjustable means associated with said amplifier for maintaining said amplifier just below the state otproducing current oscillations, a circuit controlling device in the output circuit of said amplifier normally unresponsive to. momentary current impulses, and means associating said cell with said amplifier eflective upon momentary excitation of said cell to cause said amplifier to produce sustained current oscillations for operating said relay and for maintaining said relay operated independently of the excitation of said cell.

15. In combination, a regenerative vacuum tubeamplifier, a resistance connected in the grid circuit of said amplifier, a light sensitive cell connected in a leak circuit to the grid of said amplifier, a grid polarizing battery, said battery and resistance being so proportioned that the potential applied to the grid through said resistance is sullicient to hold said amplifier just below the point of producing current oscillations when said cell is not excited but is insufficient to hold meme-as B said amplifier below the point of producing said amplifier to pass the threshold of oscil current oscillations when said cell is molation in response to a momentary excitation 10 mentarily excited. l of said cell.

16. An electrical trigger circuit compris- In testimony whereof, I have signed my ing a regenerative vacuum tube amplifier name to this specification, this 18th day of normally just below the point of generating March, 1927. sustained oscillations, and a light sensitive s device associated with said amplifier to cause J1 LOUIS REYNOLDS 

